The invention relates to a control system for independently controlling a plurality of embroidery sewing machines in accordance with numerical data stored in a set of memories which control embroidery pattern sewing operations.
Recently, embroidery sewing machines are constructed as automated units. By way of example, U.S. patent application Ser. No. 139,040 filed Apr. 10, 1980 now Pat. No. 4,280,420, discloses an embroidery frame which is coupled to a pair of X- and Y-positioning mechanisms, to which embroidery sewing data is applied to drive the embroidery frame in the directions of X- and Y-axes in an automatic manner, thus providing an automatic embroidery sewing machine. To increase the efficiency of the embroidery sewing operation, a plurality of such and other automatic embroidery sewing machines having their embroidery frames automatically positioned are subject to a parallel operation. In such parallel operation, all of the machine heads are apparently integrally driven in a synchronized manner as are all of the embroidery frames provided on the individual machines. With a parallel operation of this type, in the event the operation of one of the machines must be interrupted as a result of a thread breakage or any other trouble, the operation of the entire system must be interrupted. In addition, at any one time, every machine head is capable of forming a same and common embroidery pattern. Upon completion of sewing a single pattern, the change of thread and embroidery frames must be simultaneously performed for all of the machine heads. Hence, if a single operator controls a plurality of automatic embroidery sewing machines, the manual intervention is concentrated at one time, which stands in the way to increasing the operational efficiency.